策略模式

fengzhuang.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

public abstract class fengzhuang
{
public abstract double Cal(double a, double b);
}
public class Add : fengzhuang
{
public override double Cal(double a, double b)
{
double result = 0;
result = a + b;
return result;
}
}
public class Sub : fengzhuang
{
public override double Cal(double a, double b)
{
double result = 0;
result = a - b;
return result;
}
}
public class Mul :fengzhuang
{
public override double Cal(double a, double b)
{
double result = 0;
result = a * b;
return result;
}
}
public class Div : fengzhuang
{
public override double Cal(double a, double b)
{
double result = 0;
result = a / b;
return result;
}
}
public class Context
{
private fengzhuang calculate = null;
public Context(Calculator _cal)
{
this.calculate = _cal;       }
public double Cal(double a, double b, String symbol)
{
return this.calculate.Cal(a, b);
}
}

代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class index : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{

}
protected void Cal_Click(object sender, EventArgs e)
{
string symbol = DropDownList1.SelectedItem.ToString();
double a = Convert.ToDouble(TextBox1.Text);
double b = Convert.ToDouble(TextBox2.Text);
Context contex = null;
if (DropDownList1.SelectedIndex == 1)
{
contex = new Context(new Add());
}
else if (DropDownList1.SelectedIndex == 2)
{
contex = new Context(new Sub());
}
else if (DropDownList1.SelectedIndex == 3)
{
contex = new Context(new Mul());
}
else if (DropDownList1.SelectedIndex == 4)
{
contex = new Context(new Div());
}
string answer = contex.Cal(a, b, symbol).ToString();

string result = TextBox1.Text + DropDownList1.SelectedItem.ToString() + TextBox2.Text;
if (TextBox3.Text == answer)
{
Response.Write("<script>alert('回答正确!')</script>");
ListBox1.Items.Add(result + "=" + TextBox3.Text.Trim());
}

else
{
Response.Write("<script>alert('答题错误!')</script>");
ListBox1.Items.Add(result + "=" + TextBox3.Text.Trim() );
}
TextBox1.Text = "";
TextBox2.Text = "";
TextBox3.Text = "";
}
}

总结：看来想做成功还得伙伴。要想走得快一个人走，但要想走得远还得伙伴挽着手一起走。有人帮忙就是好